When producing printed products, two, three or more printed sheets, each of which may feature one, two or more sheets of the finished printed product are gathered at a working station and then, as appropriate, are directed for further processing. For this purpose, so-called gathering machines may be used in which the printed sheets with the aid of feeding devices in form of sheet feeders are taken from a stack of, as appropriate, folded printed sheets and deposited on a conveyor chain. Said conveyor chain in said devices is formed by a plurality of working stations which are aligned consecutively and move along a predetermined working path, whereby the printed sheets, deposited typically opened with a trailing fold and laid astride on said working stations formed by the consecutive sections of the conveyor chain, may be transported along the working path with the aid of suitable grippers and may be held at said working station.
Said gathering machines are described, for example, in EP 1 216 947 Al. The disclosure of this publication with respect to design and operation of said gathering machines is hereby included explicitly by reference.
When producing printed products from individual printed sheets it is essential, that the printed sheets of each printed product are directed to the working station in a predetermined direction and according to a predetermined sequence. In gathering machines described in EP 1 216 947 Al, the composition of each printed sheet of a given printed products is verified, by reading the information embedded in each printed sheet and characterizing each printed sheet with a suitable reading device, feeding to an inspective device and comparing to topology data of the printed product to be produced from the printed sheets, stored in said inspective device. When, by comparison of the read information and the topology data, a discrepancy is detected, the production process may be interrupted and/or the faulty printed sheet may be removed.
When carrying out said methods, it has been shown that the production of various printed products, which may contain printed sheets containing the same information, can be problematic.
When faced with these problems of the state of the art, the invention relates to a method with which the production of various printed products may be controlled simply and reliably.
According to the present invention, this may be accomplished by extension of previously known methods, characterized essentially in that during analysis, the composition information of at least one printed sheet is compared to the information derived of at least one more printed sheet used for production of the same printed product, in particular composition information.
The present invention acknowledges that for reliable testing of the composition of printed products it is not necessary to compare the composition information of all printed sheets to a data set of the entire printed product, but it is sufficient to verify that the individual printed sheets which are fed sequentially to the working station are compatible with each other. With said method, through appropriate selection of composition information, a printed sheet containing composition information may be assigned to different printed products, if only care is taken that the composition information of the other printed sheets of said printed product show a direct or indirect connection with said printed sheet. Embodiments of the present invention include in particular methods where only individual printed sheets contain composition information, the information content of which indicates, that other printed sheets do not contain the respective composition information. Of said printed sheets, information can be derived, that they do not contain separate composition information, and during analysis this information may be compared to the composition information provided on one or more of the remaining printed sheets of the printed product.
Embodiments of the present invention include methods where expediently an error signal is generated, when the result of the evaluation determined a faulty composition of the printed product. In response to the error signal, the device used for execution of said method, such as, for example, a gathering machine may be stopped and/or the faulty printed product may be removed.
As mentioned above in connection with conventional gathering machines, the printed sheets for producing printed products are typically transported sequentially to a working station. In this process, the composition information of at least one fed printed sheet may contain position information describing a printed sheet to be fed to said working station immediately before and/or afterwards, wherein during the analysis the position information of at least two printed sheets to be fed sequentially to said working station is compared to each other. The position information of the printed sheets constitutes a general description of all permissible sequences of printed products. Hereby, the position information may consist of two partial informations, the first one describing one or more printed sheets which, before feeding said sheet, are to be fed to the working station, whereas the second partial information may describe one, two or more printed sheets to be fed to said working station afterwards. Within the scope of the present invention it is also thought to include in the position information, the information that preceding or following said printed sheet there is no further printed sheet to be fed.
Besides said position information, the composition information may also contain product information indicating that a printed sheet is part of one or more printed products, and an error signal is generated when the analysis of the product information of two printed sheets to be assembled to one printed product show that the printed sheets may not be assembled to one printed product. Hereby said product information may contain two or more partial informations. In this context, it may also be thought of that individual products are part of, for example, a product group of a common order and one of the partial informations designates said product group. A second partial information may indicate that the designated printed sheet is part of a certain printed product of the product group. Thus, said information designates those printed products which are permitted to contain the respective printed sheet. If a product can be part of several products, it may be designated with special value (joker) of the partial information. This may be realized, for example, by the product information designating only a product group rather than a specific product. Furthermore, it is also thought of a partial information of the product information that represents that the designated printed sheet is only optional for the respective printed product and, if appropriate, may be replaced with a printed sheet with otherwise identical composition information.
To designate that printed sheets are part of groups of printed products, the product information, as described above, may contain partial information that designates said being part of this group. The designation of overriding groups basically may be extended indefinitely.
Within the scope of the present invention, it is also thought to include the execution of such methods in which the composition information of at least one printed sheet is compared only during production of the first printed product of a series of identical products to the information derived from at least one more printed sheet designated for production of said printed products. In this case, the method according to the present invention is only executed during set-up of the machine used for production of the printed products. In principle, with one machine set-up, only identical products may be produced with said methods. According to an embodiment of the present invention, when producing printed products in connection with the production of the first product of a series of identical products, the composition information of at least one printed sheet is compared to the composition information of the corresponding printed sheet used for the first product of the product series and an error signal is generated if the composition information of the printed sheet to be used for the production of the subsequent printed products differs from the composition information of the printed sheet used for production of the first printed product.
In another embodiment of the present invention, during production of each printed product of a series of identical products, the composition information of at least one printed sheet is compared to information derived from at least one more printed sheet used for production of said printed products. In said embodiment of said method of the present invention, printed products with differing printed sheet composition may be produced in one production cycle. When different printed products are produced as part of a product series, it may also be determined during analysis of the composition information whether the composition of individual printed sheets will lead to conforming printed products as designated by the composition information.
As described above in connection with conventional methods, the working station, for example, realized in form of a section of a conveyor chain, may be moving during the assembly of printed products along a production path, and the working station may be fed with the printed sheets necessary for production of the printed product with feeding devices arranged alongside the production path. Within the scope of the present invention, it is also thought of, as described above, feeding printed sheets for two or more printed products with one feeding device. In this case, it is advantageous when the composition information of the corresponding printed sheets is compared during production of each printed product to the information derived from at least one more printed sheet designated for production of said printed product. In any case, when executing said methods, it is useful to consider additional position information with respect to the position of the corresponding feeding device relative to the production path during analysis of the composition information. Said position information, together with the composition information may be transferred to a inspective device and/or may be stored in said inspective device and may be designated to said composition information.
Typically, it is also verified, if printed products fed by the feeding device are identical and an error signal is generated then, when composition information of a printed sheet is different from the composition information of the remaining printed sheets fed with said feeding device. If printed sheets for two or more printed products are to be fed with one feeding device, a corresponding check, without negatively impacting the reliability of the process, may take place when the composition information of the printed sheets at the feeding device designed for feeding printed sheets of two or more printed products contains a partial information, representing that it is permitted to feed printed sheets with different composition information at the corresponding feeding device. After analysis of said partial information, the generation of an error signal is prevented, when printed sheets containing different composition information are fed by said feeding device.
The above information represents additional information, which is neither associated with the product information nor the position information. Said additional information may be contained in various ways in the composition information. In this context, it is referred to, among others, to the following additional information:1. In a printed product, a printed sheet shall be present sequentially multiple times.2. A printed sheet is part of a “Coming and Going product”.3. A printed sheet may also be inserted twisted by 180°.The present invention concerns also a variable production where during composition of the printed products at least one printed sheet is selected depending on the analysis of the composition information of at least one other printed sheet. In this context, the present invention also concerns, for example, aborting individual feeding devices, if the composition information of a printed sheet shows, that there is no printed sheet to be fed to said feeding device.As already explained above, the composition information of a printed sheet may include a beginning and an ending information which represents that for assembly of a printed sheet before or after feeding said printed sheet to a working station, there is no further printed sheet to be fed to said working station, whereby an error signal is generated when a printed sheet is fed to feeding device along the production path serving to feed printed sheets containing the beginning and ending information.
Although the composition information may be captured also before or after feeding the printed sheets, it proved itself particular expedient within the scope of the present invention if at least at one feeding device the composition information provided by the printed sheet to be fed with said feeding device is captured and, as appropriate, is passed on, to a control device together with the position information representing the position of said feeding device with respect to the production path and/or with respect to other feeding devices. Hereby, said composition information may be coded according to a predetermined encoding method, for example, as a bar code, whereby decoding may take place in said inspective device. In order to increase the flexibility of methods according to the present invention, it proved to be expedient, when the composition information contains partial information representing or presenting said coding method and the control device executes the decoding according to said partial information. As already explained above, printed sheets without composition information may be fed for assembly of the printed product, their feeding being pointed out by composition information embedded in at least one printed sheet.
As shown by the above description of methods according to the present invention, a suitable device for performing said methods is characterized by a plurality of feeding devices or feeders for feeding printed sheets to a working station, whereby at least two feeding devices are designated a capturing device suitable for capturing composition information embedded in printed sheets to be fed by said devices and a control device designed to analyze composition information captured by said capturing device, mainly by the control device being able to compare composition information captured by at least two capturing devices. Hereby, working stations according to the inventive device may be realized, just like in conventional gathering machines, as individual sections of a conveyor chain, whereas the feeding devices may be realized as conventional printed sheet feeders and the capturing device may feature a bar code reader.